Urea grease composition

ABSTRACT

The present invention aims to offer a urea grease composition which excels in noise performance, has long life at high temperatures and, further, also provides the basic performance of greases such as shear stability and heat resistance, as well as appropriate oil separation properties. The present invention provides a urea grease composition comprising: a diurea compound as shown by the General Formula (A) below: R 11  NHCONHR 12 NHCONHR 13  . . . (A), (where R 11  and R 13  are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R 11  and R 13  is a dodecyl group and R 12  is a diphenylme thane group); and a diurea compound as shown by the General Formula (B) below: R 21  NHCONHR 22 NHCONHR 23  . . . (B), (where R 21  and R 23  are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R 21  and R 23  is an oleyl group, and R 22  is a diphenylmethane group).

This invention relates to novel urea grease compositions which excel in noise performance, have a long life at high temperatures and, further, also provide the basic performance of grease such as shear stability and heat resistance, as well as appropriate oil separation properties.

The foremost characteristic of urea greases using a urea compound as a thickener lies in their heat resistance and oxidative stability. Since greases which have a lubricating life at high temperatures several to ten or more times longer than the lubricating life of ordinary lithium greases have been developed, urea greases are now widely used today in many applications.

However, virtually all urea greases on the market have a poor noise performance and there are often situations where they cannot be used in many machines and apparatus where silence is nowadays required. The present situation is that the range of applications has become restricted.

For example, in the case of familiar domestic electrical appliances, in order to ensure a comfortable and silent living environment, noise countermeasures are indispensable in equipment such as cleaners, washing machines, refrigerator compressors, air-conditioner compressors and fans, electric fans and fan heaters, dryers, exhaust fans and air purifiers. Low-noise greases which have superior noise performance are actively used in the bearing greases used in the rotating parts of these appliances.

Also, because of the increased temperatures accompanying reductions in size of the apparatus and higher outputs which, in addition to noise performance, are required by these domestic appliances, long life at the higher temperatures has become a very strong requirement, depending on the type of appliance. Greases which use urea compounds having superior noise performance as a thickener and which have long life are extremely effective and the development of better products is anticipated. Naturally, the basic performance of bearing grease such as shear stability (leakage resistance), stability at high temperatures and appropriate oil separation properties will be indispensable.

In the automobile industry, too, the requirement for silence has become stronger year by year. In particular, there has been thorough research into noise and its countermeasures in high-quality saloon cars. Requirements for noise reduction in individual parts thereof are extremely severe. Here, too, the requirement for high-quality greases with excellent noise performance for use in bearings has become stronger each year. Particularly in the case of bearings used in engine parts, long life at higher temperatures has become a very strong requirement. Greases which use urea compounds having superior noise performance as a thickener and which have long life are extremely effective and the development of better products is anticipated. Naturally, as with the above-mentioned greases for domestic electrical appliances, the basic performance of the bearing greases such as shear stability (leakage resistance), stability at high temperatures and appropriate oil separation properties will be indispensable.

References in the prior art to urea greases relating to noise properties include Patent Documents 1, 2 and 3 due to the present applicant.

Japanese Laid-open Patent 1-139696 (1989) describes a thickener comprising a mixture of the diurea compounds (i) and (ii) below as shown by the following general formulas:

R³¹NHCONHR³²NHCONHR³³   (i)

R³⁴NHCONHR³⁵NHCONHR³⁶   (ii)

(where R³² is a diphenylmethane group, R³¹ and R³³ are each straight-chain or branched saturated alkyl groups having 8 carbons, R³⁵ is a tolylene group or a bitolylene group, and R³⁴ and R³⁶ are each alkyl-substituted aromatic groups or halogen-substituted aromatic groups).

Japanese Laid-open Patent 2-77494 (1990) describes a thickener comprising a mixture of the above-mentioned diurea compounds (i) and (ii) where, in the above-mentioned general formulas (i) and (ii), R³² is a bitolylene group, R³¹ and R³³ each represent a straight-chain or branched saturated alkyl groups or unsaturated alkyl groups having 18 carbons, R³⁵ is a diphenylmethane group, and R³⁴ and R³⁶ are each straight-chain or branched saturated alkyl groups having 8 carbons.

Japanese Laid-open Patent 6-17080 (1994) discloses a thickener comprising a mixture of the diurea compounds (i) and (ii) where, in the above-mentioned general formulas (i) and (ii), R³² represents a tolylene group, R³¹ and R³³ are each straight-chain or branched saturated alkyl groups or unsaturated alkyl groups having from 16 to 18 carbons, R³⁵ is a diphenylmethane group, and R³⁴ and R³⁶ are each straight-chain or branched saturated alkyl groups having 8 carbons.

References relating to noise properties include Japanese Laid-open Patent 3-28299 (1991). This document describes a grease composition where, incorporated as a thickener with a base oil containing an alkyldiphenyl ether oil as an essential constituent, is a diurea compound where, in the above-mentioned general formula (i), R³² is an aromatic hydrocarbon group having from 6 to 15 carbons, R³¹ and R³³ are straight-chain alkyl groups having from 8 to 18 carbons, and the proportion occupied by said alkyl groups having 8 carbons in R³¹ and R³³ is from 60 to 100% by mol.

Japanese Laid-open Patent 2-80493 (1990) (Page 6, Table 2) describes a composition for use in tapered roller bearings where from 0.5 to 5% by weight of oxidation-modified polyolefin and/or acid-modified polyolefin is added to and mixed with a urea grease. Table 2 there shows urea thickeners using octylamine having 8 carbons, stearylamine (octadecylamine) having 18 carbons and MDI (diphenylmethane-4,4′-diisocyanate) as raw materials, and it is demonstrated that the thickeners exhibited excellent effects such as mechanical stability, wet shear stability and pressure transferability.

Japanese Laid-open Patent 3-243696 (1991) describes a diurea compound where, in the above-described general formula (i), R³² is a 3,3′-dimethyl-4,4′-biphenylene group and R³¹ and R³³ are a mixture of an alkyl group having from 8 to 18 carbons and an oleyl group. However, there have been drawbacks with this technique in that penetration has been poor and it has not been possible to obtain greases having a penetration of around 250 unless large amounts of thickener are employed, and the degree of oil separation under high temperatures has been large.

Japanese Laid-open Patent 58-185693 (1983) describes an improved diurea-type grease in which the diurea-type grease is made to contain one or two or more of an alkenyl succinimide, a metal salt of an alkylbenzene sulphonic acid and a metal salt of petroleum sulphonic acid. It mentions that for the diurea-type grease it is possible to use diisocyanates and monoamines and that, for the monoamines, aliphatic amines such as stearylamine, and oleylamine and aromatic amines such as cyclohexylamine can typically be used. It discloses that this grease has extremely good noise properties in comparison with greases of the prior art.

Further, examples of investigating production methods in order to improve the noise properties of urea greases can be found. For example, Japanese Laid-open Patent 2-4895 (1990) describes a production method for a urea grease in which noise properties have been improved by adding an isocyanate and an amine to a base oil, effecting a reaction at a temperature of from 60 to 120° C., performing a dispersion treatment on the resultant mixture of urea compound and base oil by using a kneading apparatus, and then heating up to between 160 and 180° C. at a rate of temperature rise of from 0.5 to 2° C./min.

Japanese Laid-open Patent 3-190996 (1991) describes a production method for a grease with excellent noise properties in which a base oil in which an isocyanate has been dissolved or dispersed and a base oil in which an amine has been dissolved or dispersed are pressurised in a reaction vessel, allowing them to react by impinging and mixing with each other or allowing them to react by increasing the pressure and introducing them to rotating mixing paddles.

Further, Japanese Laid-open Patent 3-231993 (1991) describes a production method for a low-noise urea grease comprised of a first process in which a mixture of from 2 to 30% by weight of a urea compound where, in the above-mentioned general formula (i), R³¹ and R³³ are saturated alkyl groups having from 8 to 18 carbons and R³² is a tolylene group, a diphenylmethane group or a dimethyl biphenylene group, and from 98 to 70% by weight of a base oil are heated to between 170 and 230° C. to cause the urea compound to be completely dissolved in the base oil, and a second process in which, after the first process, cooling is effected at a rate of at least 5° C./min. In none of the above-mentioned Patent Documents 1 to 10 is there any description which specifically suggests the urea grease composition of this invention.

As described in the above-mentioned patent documents, there are many examples where, for the isocyanate raw material, tolylene diisocyanate (TDI) or 3,3′-dimethyl-4,4′-biphenylene diisocyanate (TODI) are used in order to offer urea greases with excellent noise properties. Also, examples are given for production methods in which two or more different kinds of grease are mixed after a reaction process using a kneading apparatus or a high-pressure kettle so that there is no aggregation of the urea compound, and then heating and dissolving the greases.

As the quantities of urea greases produced become greater and the demand for greases with superior noise properties intensifies in the market-place, cleaner working environments for production of the greases and better noise properties in the final commercial product are being sought.

Many users seek high-performance greases at low prices. Urea greases which use TODI, which is expensive as a raw material, in complex manufacturing procedures cannot compete in the market-place.

And as regards grease manufacture, too, because of the increase in the quantities manufactured thereof, it is necessary to be even more careful in handling the TDI raw material (which is classified as a Class 2 Specified Chemical Substance under the Industrial Safety and Health Law), and in order to improve noise properties qualitatively, it is necessary to give consideration to reinforcing apparatus and extending manufacturing process times.

This invention provides a urea grease composition which excels in noise performance, has long life at high temperatures and, further, also provides the basic performance of grease such as shear stability and heat resistance, as well as appropriate oil separation properties.

Having taken careful cognisance of the problems and requirements in the marketplace, and by dint of thorough investigation and analysis, as well as intense research, of the structural components of urea thickening agents in urea grease compositions, the inventors have discovered that by limiting themselves to urea grease compositions incorporating certain specified urea thickening agents within the structural components of the urea, the result is an excellent urea grease composition which excels in noise performance, has long life at high temperatures and, further, also provides the basic performance of grease such as shear stability and heat resistance, as well as appropriate oil separation properties. They have thus arrived at this invention.

In other words, this invention provides a urea grease composition comprising:

a diurea compound as shown by the General Formula (A) below:

R¹¹NHCONHR¹²NHCONHR¹³   (A),

(where R¹¹ and R¹³ are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R¹¹ and R¹³ is a dodecyl group and R¹² is a diphenylmethane group); and a diurea compound as shown by the General Formula (B) below:

R²¹NHCONHR²²NHCONHR²³   (B),

(where R²¹ and R²³ are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R²¹ and R²³ is an oleyl group, and R²² is a diphenylmethane group).

Preferably the proportion occupied by the dodecyl group in R¹¹ and R¹³ in the above-mentioned General Formula (A) is from 2 to 70% by mol and/or the proportion occupied by the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is from 5 to 70% by mol.

Further it is preferred when a hydrocarbon group having from 6 to 20 carbons other than the dodecyl group(s) in R¹¹ and R¹³ in the above-mentioned General Formula (A) and/or a hydrocarbon group having from 6 to 20 carbons other than the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is an octyl group.

It is even more preferred that the proportion occupied by the dodecyl group in R¹¹ or R¹³ in the above-mentioned General Formula (A) is from 3 to 55% by mol, the proportion occupied by the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is from 5 to 55% by mol, and the proportion occupied by the octyl group(s) in R¹¹, R¹³, R²¹, and R²³ is from 10 to 90% by mol.

In a further aspect this invention provides a urea grease composition comprising:

diurea compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR³   (a)

and

R³NHCONHR²NHCONHR³   (b)

and, further, a diurea compound or compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR⁴   (d)

and/or

R³NHCONHR²NHCONHR⁴,   (e)

(where R² is a diphenyl methane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).

In an even further aspect this invention provides a urea grease composition comprising:

diurea compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR¹   (a)

and

R³NHCONHR²NHCONHR³   (b)

and

R¹NHCONHR²NHCONHR³   (c)

and, further, a diurea compound or compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR⁴   (d)

and/or

R³NHCONHR²NHCONHR⁴,   (e)

(where R² is a diphenyl methane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).

Further this invention provides a urea grease composition comprising:

(i) a diurea compound as shown by the above-mentioned general formula (a); and

(ii) diurea compounds being diurea compounds selected from the group comprising

(1) the above-mentioned general formulas (b), (c), (d) and (e)

(2) the above-mentioned general formulas (b), (c) and (d)

(3) the above-mentioned general formulas (b), (c) and (e),

and the molar ratio of the diurea compound as shown by the above-mentioned general formula (a) in relation to the totality of diurea compounds is from 20 to 80% by mol.

Also, this invention provides a urea grease composition comprising:

a diurea compound as shown by the general formula:

R¹NHCONHR²NHCONHR³   (c)

and, further, a diurea compound or compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR⁴   (d)

and/or

R³NHCONHR²NHCONHR⁴,   (e)

(where R² is a diphenyl methane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).

In an even further aspect this invention provides a urea grease composition comprising:

diurea compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR³   (c)

and

R³NHCONHR²NHCONHR³   (b)

and, further, a diurea compound or compounds as shown by the general formulas:

R¹NHCONHR²NHCONHR⁴   (d)

and/or

R³NHCONHR²NHCONHR⁴,   (e)

(where R² is a diphenyl methane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).

Also, this invention provides a urea grease composition comprising:

(i) a diurea compound as shown by the above-mentioned general formula (c); and

(ii) diurea compounds being diurea compounds selected from the group comprising

(1) the above-mentioned general formulas (b), (d) and (e)

(2) the above-mentioned general formulas (b) and (d)

(3) the above-mentioned general formulas (b) and (e) and the molar ratio of the diurea compound as shown by the above-mentioned general formula (c) in relation to the totality of diurea compounds is from 20 to 80% by mol.

Compounds as shown by the above-mentioned General Formula (A) may normally be prepared in accordance with the reaction equation below:

[Formula 1]

OCN—R¹²—NCO+R¹¹NH₂+R¹³NH₂→R¹¹NHCONHR¹²NHCONHR¹³+R¹³NHCONHR¹²NHCONHR¹¹+R¹³NHCONHR¹²NHCONHR¹³

(where R¹¹, R¹² and R¹³ are as described before).

Also, compounds as shown by the above-mentioned General Formula (B) may be prepared in similar fashion to the compounds as shown by General Formula (A).

[Formula 2]

OCN—hu 22—NCO+R²¹NH₂+R²³NH₂→R²¹NHCONHR²²NHCONHR²³+R²¹NHCONHR²²NHCONHR²¹+R²³NHCONHR²²NHCONHR²³

(where R²¹, R²² and R²³ are as described before).

The compounds corresponding to the above-mentioned OCN—R¹²—NCO and OCN—R²²—NCO are both diphenylmethane-4,4′-diisocyanate.

In order to introduce R¹¹ and R¹³ in compounds of the aforementioned General Formula (A), R¹¹NH₂ and R¹³NH₂ are used, and in order to introduce R²¹ and R²³ in compounds of the aforementioned General Formula (B), R²¹NH₂ and R²³ NH₂ are used.

The invention is explained in detail below in relation to compounds of General Formulas (A) and (B) and general formulas (a) to (e).

The dodecyl group and in particular n-dodecyl group 25 in either of the aforementioned R¹¹ and R¹³ imparts heat resistance to the urea grease and, by its presence, can extend the life of the urea grease at high temperatures.

However, if both R¹¹ and R¹³ are dodecyl groups, the noise performance is poor even though the heat resistance is good. Therefore, if either one of R¹¹ and R¹³ is made a dodecyl group, the other may be a hydrocarbon group of from 6 to 20 carbons, and preferably an oleyl group or an octyl group. Specific examples of raw materials which supply dodecyl groups preferably include straight-chain primary dodecylamines. A urea thickening agent comprising a mixture of a dodecylamine and oleylamine or octylamine with diphenylmethane-4,4′-diisocyanate has excellent thermal stability and grease compositions using this are not apt to change at high temperatures, so that the effect on extending life is extremely large. The dodecyl group may occupy from 2 to 70% by mol, and preferably from 4 to 50% by mol, in respect of the total molar number of R¹¹ and R¹³ in the aforementioned General Formula (A).

At least one of the aforementioned R²¹ and R²³ is an oleyl group and in particular an n-oleyl group. The presence of the oleyl group not only imparts excellent noise performance to the urea grease composition, but the adsorption properties of the urea grease composition in respect of the metal surfaces which form the sliding portions of machine parts become better, and so the lubricating properties are further improved. The oleyl group may occupy from 5 to 70% by mol, and preferably from 8 to 55% by mol, in R²¹ and R²³ in the aforementioned General Formula (B).

In this invention it is indispensable that at least an oleyl group and a dodecyl group, particularly an n-dodecyl group, are incorporated in the diurea grease composition, but preferably an octyl group, particularly an n-octyl group, is also incorporated.

If an oleyl group and a dodecyl group are added and an octyl group, particularly an n-octyl group, is further incorporated, it is appropriate if the proportion occupied by the dodecyl group in R¹¹ and R¹³ in the aforementioned General Formula (A) is from 3 to 55% by mol, and further the proportion occupied by the oleyl group in R²¹ and R²³ in the aforementioned General Formula (B) is from 5 to 55% by mol, while the proportion occupied by the octyl groups in R¹¹, R¹³, R²¹ and R²³ is from 10 to 90% by mol.

Thickening agents encompassed by General Formulas (A) and (B) which are characteristic of this invention may be used in the proportion such that they occupy from 20 to 100% by mol of the total thickening agent.

The thickening agents comprising diurea compounds as shown by the aforementioned General Formulas (A), (B) and (a) to (e) may preferably be incorporated in the amount of from 2 to 30% by weight relative to the mineral oils or synthetic oils or mixtures thereof which form the lubricating oil. If the diurea compound which is the thickening agent is less than 2% by weight relative to the mineral oils or synthetic oils or mixtures thereof which form the lubricating oil, the thickening effect becomes too small and the grease may become too soft, with the risk, for example, of leakage. If it exceeds 30% by weight, the grease may become too hard and its flow resistance increase, so that sufficient lubricating effect is not obtained in that the friction torque increases and ability to penetrate decreases. Also, the cost increases.

For the lubricating base oils in this invention, those generally used as lubricating oils and base oils for greases may be used. They are not specially limited, but as examples mention may be made of mineral oils and/or synthetic oils and plant oils. Specific examples of synthetic oils are GTL-derived base oils (produced by the Fischer-Tropsch process), polyolefins such as α-olefin oligomers and polybutenes, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, diesters such as di-2-ethylhexylsebacate and di-2-ethylhexyladipate, polyol esters such as trimethylolpropane ester and pentaerythritol ester, perfluoroalkyl ethers, silicone oils and polyphenyl ethers, and as typical examples of plant oils mention may be made of castor oil and rapeseed oil. Examples may be given of using these base oils singly or in mixtures, but they do not limit the invention.

Also, it is possible further to add to the composition of the invention additives such as anti-oxidants and rust preventatives, oiliness agents and extreme-pressure additives, as well as anti-wear agents and solid lubricants or metal deactivators and polymers. For example, anti-oxidants include 2,6-di-tertiary-butyl-4-methylphenol, 2,6-di-tertiary-butyl-para-cresol, P,P′-dioctyldiphenylamine, N-phenyl-α-naphthylamine and phenothiazines. Rust preventatives include paraffin oxide, metal-salts of carboxylic acids, metal salts of sulphonic acids, carboxylic acid esters, sulphonic acid esters, salicylic acid esters, succinic acid esters, sorbitan esters and various amine salts. Oiliness agents and extreme-pressure additives as well as anti-wear agents include sulphurised zinc dialkyl dithiophosphates, sulphurised zinc diallyl dithiophosphates, sulphurised zinc dialkyl dithiocarbamates, sulphurised zinc diallyl dithiocarbamates, sulphurised molybdenum dialkyl dithiophosphates, sulphurised molybdenum diallyl dithiophosphates, sulphurised molybdenum dialkyl dithiocarbamates, sulphurised molybdenum diallyl dithiocarbamates, organic molybdenum complexes, sulphurised olefins, triphenylphosphates, triphenylphosphorothionates, tricresylphosphates, other phosphate esters and sulphurised fats and oils. Solid lubricants include molybdenum disulphide, graphite, boron nitride, melamine cyanurate, PTFE (polytetrafluororethylene), tungsten disulphide and graphite fluoride. Metal deactivators include N,N′-disalicylidene-1,2-diaminopropane, benzotriazole, benzoimidazole, benzothiazole and thiadiazole. As examples of polymers, mention may be made of polybutenes, polyisobutenes, polyisobutylenes, polyisoprenes and polymethacrylates.

By means of this invention it is possible to provide a novel urea grease composition which excels in noise performance, has long high-temperature life with high dropping point, and, further, also provides the basic performance of greases such as shear stability and heat resistance, as well as appropriate oil separation properties.

EXAMPLES

The invention is explained in detail below by means of examples and comparative examples, but the invention is in now way limited by these examples.

The abbreviations relating to the raw material constituents of the thickeners and the base oils used in the examples and comparative examples in Tables 1 to 5 below are as described next.

Isocyanate A is diphenylmethane-4,4′-diisocyanate, the molecular weight being 250.26.

Isocyanate B is tolylene diisocyanate, the molecular weight being 174.16.

For the amine raw materials:

Amine A is a straight-chain primary amine of average molecular weight 128.7 where the main constituent (at least 90%) is a saturated alkyl group of 8 carbons (industrial octylamine);

Amine B is a straight-chain primary amine of average molecular weight 255.0 where the main constituent (at least 70%) is an unsaturated alkyl group of 18 carbons (industrial oleylamine); and

Amine C is a straight-chain primary amine of average molecular weight 184.6 where the main constituent (at least 90%) is a saturated alkyl group of 12 carbons (industrial dodecylamine).

Also, the kinetic viscosity at 100° C. of the mineral oil shown in the examples and comparative examples is 10.12 mm²/s, while synthetic oil A refers to a poly-α-olefin oil, the kinetic viscosity being 12.70 mm²/s at 100° C. and synthetic oil B refers to an alkyldiphenyl ether oil, the kinetic viscosity being 12.69 mm²/s at 100° C.

a, b, c, d and e in the thickener mol % columns given in Tables 1 to 4 each denote urea compounds that can be expressed by:

R¹NHCONHR²NHCONHR¹   (a)

R³NHCONHR²NHCONHR³   (b)

R¹NHCONHR²NHCONHR³   (c)

R¹NHCONHR²NHCONHR⁴   (d)

R³NHCONHR²NHCONHR⁴   (e)

(where R² is a diphenylmethane group, R¹ is a hydrocarbon group of from 6 to 10 carbons having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having an n-dodecyl group as its main constituent).

Also, a and b in the thickener mol % column for the comparative examples given in Table 5 denote the above-mentioned compounds given for the examples of Tables 1 to 4, and f, g, h, i and j in the thickener mol % columns for the examples given in Tables 1 to 4 each denote urea compounds that can be expressed by:

R⁴NHCONHR²NHCONHR⁴   (f)

R¹NHCONHR⁵NHCONHR¹   (g)

R³NHCONHR⁵NHCONHR³   (h)

R⁴NHCONHR⁵NHCONHR⁴   (i)

R¹NHCONHR⁵NHCONHR⁴   (j)

(where R⁵ is a tolylene group, R¹ is a hydrocarbon group of from 6 to 10 carbons having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having an n-dodecyl group as its main constituent).

Tests on the properties of the examples and comparative examples were carried out by the following methods.

1. Penetration: JIS K2220

2. Dropping point: JIS K2220

3. Oil separation: JIS K2220 Method B, conditions being 100° C. and 24 hours.

4. Noise test: Measured by the method of Japanese Patent 53-2357 (1978).

5. Shell roll: ASTM D1831

6. Bearing life test: ASTM D3336

Greases of this invention were obtained by synthesising urea compounds, the thickening agents, in lubricating base oil using the proportions shown in Tables 1 and 2, and by blending in additives.

Example 1

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine B (industrial oleylamine) which were constituent B3 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which were constituent B4 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. After again agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which were constituent B5 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 1.

Example 2

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine B (industrial oleylamine) which were constituent 53 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which were constituent B4 and which had been mixed and dissolved in lubricating base oil in advance were-fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 2.

Example 3

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine B (industrial oleylamine) which were constituent B3 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which were constituent B5 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 3.

Example 4

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heating, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which were constituent B4 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. After again agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which were constituent B5 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 4.

Example 5

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed inside the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which were constituent B4 and which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 5.

Examples 6 and 7

With the blending proportions shown in Table 2, lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed inside the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Examples 6 and 7.

Example 8

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which was constituent B1 and which had been mixed in lubricating base oil was added and reacted with constituent A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 8.

Example 9

Lubricating base oil and isocyanate A which was constituent A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance were added from a hopper and reacted with isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After further agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remaining isocyanate A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. After again agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 9.

Example 10

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed in lubricating base oil were added from a hopper and reacted with isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating again for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remaining isocyanate A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 10.

Example 11

With the blending proportions shown in Table 3, lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed in lubricating base oil was added from a hopper and reacted with the isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating again for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remaining isocyanate A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 11.

Example 12

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed in lubricating base oil were added from a hopper and reacted with isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. After agitating again for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remaining isocyanate A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 12.

Example 13

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed in lubricating base oil were added from a hopper and reacted with isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 13.

Example 14

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) and amine B (industrial oleylamine) which had been mixed in lubricating base oil were added from a hopper and reacted with isocyanate A. Urea compound ‘c’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 14.

Example 15

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) which was constituent A were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added and reacted with isocyanate A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then, after agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 15.

Example 16

With the blending proportions shown in Table 4, lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) which was constituent A were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added and reacted with isocyanate A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. Then after agitating for 5 minutes, amine B (industrial oleylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘e’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 16.

Example 17

Lubricating base oil (a mixture of a mineral oil and synthetic oil A) and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added and reacted with isocyanate A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 17.

Example 18

Lubricating base oil (synthetic oil B) and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added and reacted with isocyanate A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which was constituent B2 and which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle and reacted with the remainder of isocyanate A which was constituent A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. After agitating for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle and reacted with the remaining isocyanate A which was constituent A. Urea compound ‘d’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Example 18.

Comparative Example 1

With the blending proportions shown in Table 5, lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added from a hopper and reacted with isocyanate A. Urea compound ‘a’ as shown by the formula

(octyl)-NHCONH-(diphenylmethane)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘f’ as shown by the formula

(dodecyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Comparative Example 1.

Comparative Example 2

Lubricating base oil and isocyanate A (diphenylmethane-4,4′-diisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine B (industrial oleylamine) which had been mixed in lubricating base oil was added from a hopper and reacted with isocyanate A. Urea compound ‘b’ as shown by the formula

(oleyl)-NHCONH-(diphenylmethane)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate A. Urea compound ‘f’ as shown by the formula

(dodecyl)-NHCONH-(diphenylmethane)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Comparative Example 2.

Comparative Example 3

Lubricating base oil and isocyanate B (tolylenediisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added from a hopper and reacted with isocyanate B. Urea compound ‘g’ as shown by the formula

(octyl)-NHCONH-(tolylene)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine B (industrial oleylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate B. Urea compound ‘h’ as shown by the formula

(oleyl)-NHCONH-(tolylene)-NHCONH-(oleyl)

was obtained. After agitating again for 5 minutes, amine A (industrial octylamine) and amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance were fed into the kettle from a hopper and reacted with the remaining isocyanate B. Urea compound ‘j’ as shown by the formula

(octyl)-NHCONH-(tolylene)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Comparative Example 3.

Comparative Example 4

Lubricating base oil and isocyanate B (tolylenediisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine A (industrial octylamine) which had been mixed in lubricating base oil was added from a hopper and reacted with isocyanate B. Urea compound ‘g’ as shown by the formula

(octyl)-NHCONH-(tolylene)-NHCONH-(octyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate B. Urea compound ‘i’ as shown by the formula

(dodecyl)-NHCONH-(tolylene)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Comparative Example 4.

Comparative Example 5

Lubricating base oil and isocyanate B (tolylenediisocyanate) were fed into a closed prototype grease kettle apparatus, and this was heated, while agitating, to 60° C. Amine B (industrial oleylamine) which had been mixed in lubricating base oil was added and reacted with isocyanate B. Urea compound ‘h’ as shown by the formula

(oleyl)-NHCONH-(tolylene)-NHCONH-(oleyl)

was obtained. The contents rose to approximately 80° C. through the heat of the reaction. That temperature was maintained for 10 minutes and then amine C (industrial dodecylamine) which had been mixed and dissolved in lubricating base oil in advance was fed into the kettle from a hopper and reacted with the remainder of isocyanate B. Urea compound is as shown by the formula

(dodecyl)-NHCONH-(tolylene)-NHCONH-(dodecyl)

was obtained. Then after quickly restarting heating, the temperature was raised to 170° C. and that temperature was maintained for approximately 30 minutes to complete the reaction. After maintaining the temperature for 30 minutes, cooling began, and at 125° C. during the cooling process, 1.0% by mass, as an extraneous proportion, of octyldiphenylamine, which is an anti-oxidant, was added to the grease. After allowing further cooling to 80° C., the grease was treated in a three-roll mill to give the grease of Comparative Example 5.

TABLE 1 Example 1 2 3 4 5 Constituent A Isocyanate A (g) 44.7 44.9 44.2 44.6 44.8 Constituent B1 Amine A (g) 36.5 36.5 36.5 36.5 36.5 Constituent B2 Amine B (g) 4.0 5.4 5.4 5.4 8.1 Constituent B3 Amine A (g) 1.2 1.6 1.6 — — Amine B (g) 2.4 3.2 3.2 — — Constituent B4 Amine A (g) 1.4 1.8 — 1.8 2.7 Amine C (g) 2.0 2.6 — 2.6 3.9 Constituent B5 Amine B (g) 1.6 — 2.2 2.2 — Amine C (g) 2.2 — 2.9 2.9 — Lube Mineral oil (g) 704 704 704 704 704 oil Synthetic oil A (g) — — — — — Synthetic oil B (g) — — — — — Total (g) 800 800 800 800 800 Amount of thickener (%) 12.0 12.0 12.0 12.0 12.0 Thickener blend a/(b + c + d + e) = a/(b + c + d) = a/(b + c + e) = a/(b + d + e) = a/(b + d) = proportions (mol %) 75/25 75/25 75/25 75/25 75/25 Penetration 267 262 255 268 263 Dropping point (° C.) 249 255 250 248 252 Oil separation (mass %) 0.6 0.4 0.4 0.5 0.6 Noise test (after 120 sec) 8 10 7 11 8 Shell roll Room temperature, 24 h 340 335 329 358 335 150° C., 24 h 348 350 317 310 353 Bearing life test, 150° C. Life h 785 — — 800 813

TABLE 2 Example 6 7 8 9 10 Isocyanate A (g) 43.8 40.3 39.7 37.5 37.7 Amine A (g) 36.4 24.3 12.2 — — Amine B (g) 8.1 16.1 24.2 5.4 8.1 Amine A (g) — — — 14.6 14.6 Amine B (g) — — — 29.0 29.0 Amine A (g) — — 8.2 1.8 2.7 Amine C (g) — — 11.7 2.6 3.9 Amine B (g) 3.3 6.5 — 2.2 — Amine C (g) 4.4 8.8 — 2.9 — Lube Mineral oil (g) 704 704 704 704 704 oil Synthetic oil A (g) — — — — — Synthetic oil B (g) — — — — — Total (g) 800 800 800 800 800 Amount of thickener (%) 12.0 12.0 12.0 12.0 12.0 Thickener blend a/(b + e) = a/(b + e) = a/(b + d) = c/(b + d + e) = c/(b + d) = proportions (mol %) 75/25 50/50 25/75 75/25 75/25 Penetration 258 256 255 238 235 Dropping point (° C.) 248 247 241 255 257 Oil separation (mass %) 1.1 2.9 3.7 0.7 0.5 Noise test (after 120 sec) 7 8 11 10 8 Shell roll Room temperature, 24 h 342 349 359 358 355 150° C., 24 h 357 371 368 353 350 Bearing life test, 150° C. Life h 772 — 756 821 —

TABLE 3 Example 11 12 13 14 15 Isocyanate A (g) 36.6 38.1 39.1 35.6 18.7 Amine A (g) — — — — 15.2 Amine B (g) 8.1 — — — 3.4 Amine A (g) 14.6 14.6 14.6 4.9 — Amine B (g) 29.0 28.9 28.9 9.6 — Amine A (g) — 2.7 5.7 — 1.1 Amine C (g) — 3.9 7.6 — 1.6 Amine B (g) 3.3 3.3 — 19.3 — Amine C (g) 4.4 4.4 — 26.6 — Lube Mineral oil (g) 704 704 704 704 760 oil Synthetic oil — — — — — A (g) Synthetic oil — — — — — B (g) Total (g) 800 800 800 800 800 Amount of thickener 12.0 12.0 12.0 12.0 5.0 (%) Thickener blend c/(b + e) = c/(d + e) = c/d = c/e = a/(b + d) = proportions (mol %) 75/25 75/25 75/25 25/75 75/25 Penetration 256 253 248 254 387 Dropping point (° C.) 249 255 259 238 238 Oil separation 0.5 0.4 0.4 0.6 5.7 (mass %) Noise test 11 12 9 8 19 (after 120 sec) Shell roll Room temperature, 351 353 351 384 >440 24 h 150° C., 353 341 346 336 424 24 h Bearing life test, 150° C. Life h — — 742 734 720

TABLE 4 Example 16 17 18 Isocyanate A (g) 77.3 44.8 44.8 Amine A (g) 46.7 36.5 36.5 Amine B (g) 30.9 8.1 8.1 Amine A (g) — — — Amine B (g) — — — Amine A (g) — 2.7 2.7 Amine C (g) — 3.9 3.9 Amine B (g) 12.4 — — Amine C (g) 16.7 — — Lube Mineral oil (g) 616 140 oil Synthetic oil A (g) — 564 — Synthetic oil B (g) — — 704 Total (g) 800 800 800 Amount of thickener (%) 23.0 12.0 12.0 Thickener blend proportions a/(b + e) = a/(b + d) = a/(b + d) = (mol %) 50/50 75/25 75/25 Penetration 187 283 258 Dropping point (° C.) >260 251 259 Oil separation (mass %) 0.1 1.1 0.4 Noise test (after 120 sec) 6 13 8 Shell roll Room temperature, 24 h 268 349 333 150° C., 24 h 259 363 355 Bearing life test, 150° C. Life h — 3,040 2,910

TABLE 5 Comparative Example 1 2 3 4 5 Isocyanate A (g) 43.1 35.2 — — — Isocyanate B (g) — — 45.6 43.5 34.5 Amine A (g) 24.3 — 53.6 35.7 — Amine B (g) — 32.2 11.1 — 44.7 Amine C (g) 28.6 28.6 — 40.8 40.8 Amine A (g) — — — — — Amine B (g) — — — — — Amine A (g) — — 4.0 — — Amine C (g) — — 5.7 — — Amine B (g) — — — — — Amine C (g) — — — — — Lube Mineral oil (g) 704 704 680 680 680 oil Synthetic oil — — — — — A (g) Synthetic oil — — — — — B (g) Total (g) 800 800 800 800 800 Amount of thickener 12.0 12.0 15.0 15.0 15.0 (%) Thickener blend a/f = b/f = g/(h + j) = g/i = h/i = proportions (mol %) 50/50 50/50 75/25 50/50 50/50 Penetration 318 304 349 388 351 Dropping point (° C.) >260 238 218 250 223 Oil separation 3.4 6.1 — — — (mass %) Noise test 1,645 1,128 13 572 89 (after 120 sec) Shell roll Room temperature, 363 369 >440 >440 >440 24 h 150° C., 24 h 345 >440 >440 >440 >440 Bearing life test, 150° C. Life h 825 — 458 — 695 

1. A urea grease composition comprising: a diurea compound as shown by the General Formula (A) below: R¹¹NHCONHR¹²NHCONHR¹³   (A), (where R¹¹ and R¹³ are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R¹¹ and R¹³ is a dodecyl group and R¹² is a diphenylmethane group); and a diurea compound as shown by the General Formula (B) below: R²¹NHCONHR²²NHCONHR²³   (B), (where R²¹ and R²³ are groups selected from the group consisting of hydrocarbon groups having from 6 to 20 carbons, at least one of R²¹ and R²³ is an oleyl group, and R²² is a diphenylmethane group).
 2. A urea grease composition according to claim 1, wherein the proportion occupied by the dodecyl group in R¹¹ and R¹³ in the above-mentioned General Formula (A) is from 2 to 70% by mol and/or the proportion occupied by the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is from 5 to 70% by mol.
 3. A urea grease composition according to claim 1, wherein the hydrocarbon group having from 6 to 20 carbons other than the dodecyl group in R¹¹ and R¹³ in the above-mentioned General Formula (A) and/or the hydrocarbon group having from 6 to 20 carbons other than an oleyl group in R²¹ and R²³ in the above-mentioned General Formula (B) is an octyl group.
 4. A urea grease composition according to claim 3, wherein the proportion occupied by the dodecyl group in R¹¹ or R¹³ in the above-mentioned General Formula (A) is from 3 to 55% by mol, the proportion occupied by the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is from 5 to 55% by mol, and the proportion occupied by the octyl groups in R¹¹, R¹³, R²¹, and R²³ is from 10 to 90% by mol.
 5. A urea grease composition comprising: diurea compounds as shown by the general formulas: R¹NHCONHR²NHCONHR¹   (a) and R³NHCONHR²NHCONHR³   (b) and, further, a diurea compound or compounds as shown by the general formulas: R¹NHCONHR²NHCONHR⁴   (d) and/or R³NHCONHR²NHCONHR⁴,   (e) (where R² is a diphenylmethane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of an oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).
 6. A urea grease composition according to claim 5 further comprising: a diurea compound as shown by the general formula: R¹NHCONHR²NHCONHR³.   (c)
 7. A urea grease composition according to claim 6 wherein the molar ratio of the diurea compound as shown by the above-mentioned general formula (a) in relation to the totality of diurea compounds is from 20 to 80% by mol.
 8. A urea grease composition comprising: a diurea compound as shown by the general formula: R¹NHCONHR²NHCONHR³   (c) and, further, a diurea compound or compounds as shown by the general formulas: R¹NHCONHR²NHCONHR⁴   (d) and/or R³NHCONHR²NHCONHR⁴,   (e) (where R² is a diphenylmethane group, R¹ is a hydrocarbon group having an octyl group as its main constituent, R³ is a hydrocarbon group having from 14 to 20 carbons and containing at least 20% by mol of oleyl group, and R⁴ is a hydrocarbon group having a dodecyl group as its main constituent).
 9. A urea grease composition according to claim 8 additionally comprising: a diurea compound as shown by the general formula: R³NHCONHR²NHCONHR³.   (b)
 10. A urea grease composition according to claim 9 wherein the molar ratio of the diurea compound as shown by the above-mentioned general formula (c) in relation to the totality of diurea compounds is from 20 to 80% by mol.
 11. Method of improving the noise performance, by using a urea grease composition according to claim
 1. 12. Use of the urea grease composition according to claim 1 for improving the noise performance.
 13. A urea grease composition according to claim 2, wherein the hydrocarbon group having from 6 to 20 carbons other than the dodecyl group in R¹¹ and R¹³ in the above-mentioned General Formula (A) and/or the hydrocarbon group having from 6 to 20 carbons other than an oleyl group in R²¹ and R²³ in the above-mentioned General Formula (B) is an octyl group.
 14. A urea grease composition according to claim 13, wherein the proportion occupied by the dodecyl group in R¹¹ or R¹³ in the above-mentioned General Formula (A) is from 3 to 55% by mol, the proportion occupied by the oleyl group(s) in R²¹ and R²³ in the above-mentioned General Formula (B) is from 5 to 55% by mol, and the proportion occupied by the octyl groups in R¹¹, R¹³, R²¹, and R²³ is from 10 to 90% by mol. 